Evaluation of neutron economical effect of new cladding materials in light water reactors

Oizumi, Akito   ; Akie, Hiroshi  ; Iwamoto, Nobuyuki  ; Kugo, Teruhiko 

Iron (Fe), nickel (Ni), titanium (Ti), niobium (Nb) and vanadium (V) are selected as possible component elements to cover a variety of new cladding materials for light water reactors (LWRs). The effect of larger thermal absorption cross sections of these elements than those of zirconium (Zr), together with those of silicon carbide (SiC), on the neutron economy in LWRs is evaluated by performing pin cell burnup calculations for a conventional pressurized water reactor (PWR), a low moderation high burnup LWR (LM-LWR) and a high moderation high burnup LWR (HM-LWR). As can be anticipated from the thermal cross sections, SiC has excellent neutron economy. The materials other than SiC largely decreases discharge burnup in comparison with Zircaloy (Zry). Among such elements of larger thermal absorption cross section, Nb has neutron economical advantage over the other materials except SiC in softer neutron spectrum reactors such as HM-LWR in which the atomic number ratio of hydrogen to heavy metal is 6. In the conventional LWRs, stainless steel of low Ni contents is as well as Nb for cladding material. The results of the analyses are summarized for the purpose to provide reference data for new cladding material development studies, in terms of the relation between fuel enrichment and cladding thickness from the viewpoint to achieve the same discharge burnup as the Zry cladding.